Re: qemu 4.2.0 audiodev soundhw

Re: qemu 4.2.0 audiodev soundhw

[Philippe Mathieu-Daudé]

Hi Jakob,

On 4/21/20 12:06 AM, Jakob Bohm wrote:
[...]
> 
> In fact, over the years, I have found it excruciatingly difficult to find
> valid qemu documentation, as each feature effort tends to leave behind
> half-updated pages and a bunch of uncoordinated messages about what may or
> may not have been implemented in unspecified versions.
I feel your pain and agree.

How can this get improved?

Keeping the command line backward compatible is not an easy task.

There is a quite important effort in progress to improve the documentation.

Users reporting bad/incomplete/outdated documentation would help and 
motivate developers to fix it. That would reduce the gap between 
developers implementing features and users.

Do you other have suggestions about what should be improved?

Thanks,

Phil.

> 
> On 20/04/2020 19:54, Idar Lund wrote:
>> Hi,
>>
>> Thanks for your response!
>>
>> Yes, I agree with you on the options. If you guys decide on (3), I 
>> would suggest to make it dynamically like this; "-soundhw 
>> hda,audiodev=sound1". This would then copy the 'audiodev' (and 
>> possible other) parameter(s) to the '-device' option.
>>
>> My personal preference would be to recommend option number 1.
>> The reason for this is that maintaining a shortcut like this makes it 
>> hard to maintain for developers when adding features and fixes bugs on 
>> other options. And of course documentation maintainers :)
>> The second reason as I see it is that people tend to create a .sh 
>> script or similar to start their qemu virtual machines if they don't 
>> use libvirt/xml schema. And for that, a more verbose command would 
>> actually be easier to maintain for users since we then know where to 
>> put parameters like this.
>>
>> -Idar
>>
>> On Mon, Apr 20, 2020 at 4:44 PM Gerd Hoffmann <kraxel@redhat.com 
>> <mailto:kraxel@redhat.com>> wrote:
>>
>>     On Fri, Apr 17, 2020 at 12:15:30PM +0100, Peter Maydell wrote:
>>     > On Fri, 17 Apr 2020 at 12:08, Idar Lund <idarlund@gmail.com
>>     <mailto:idarlund@gmail.com>> wrote:
>>     > > I'm using qemu-system-x86_64 with the following options:
>>     > > -audiodev pa,id=sound1,server=/run/user/1000/pulse/native \
>>     > > -soundhw hda
>>     > >
>>     > > After upgrade to 4.2.0 (qemu-4.2.0-7.fc32) I get the following
>>     warning:
>>     > > (qemu) audio: Device hda: audiodev default parameter is
>>     deprecated, please specify audiodev=sound1
>>     > >
>>     > > The documentation `man qemu-system-x86_64` seems to not
>>     reflect this.
>>     > > How am I supposed to use audiodev and soundhw?
>>     >
>>     > This looks like another question for you, Gerd...
>>
>>     Hmm, good question how to proceed here best ...
>>
>>     "-soundhw hda" is a shortcut for "-device intel-hda -device
>>     hda-duplex"
>>
>>     You can use "-device intel-hda -device hda-duplex,audiodev=sound1" to
>>     make the warning go away.  That is pretty verbose when compared to
>>     "-soundhw hda" though ...
>>
>>     So the options I see are:
>>
>>       (1) deprecate the -soundhw shortcut, expect users to use -device
>>           instead.
>>       (2) have -soundhw lookup the audiodev and add it automatically.
>>     Works
>>           only with a single audiodev, but that isn't different from what
>>           we have today.  If you want do more complicated things you
>>           already have to use the more verbose -device command line.
>>       (3) add audiodev option to -soundhw.
>>
>>     I don't like (3) much, our command line is already messy enough.
>>     So my
>>     personal preference would be (1) or (2) ...
>>
> 
> Enjoy
> 
> Jakob

Re: qemu 4.2.0 audiodev soundhw

[BALATON Zoltan]

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On Wed, 22 Apr 2020, Philippe Mathieu-Daudé wrote:
> Hi Jakob,
>
> On 4/21/20 12:06 AM, Jakob Bohm wrote:
> [...]
>> 
>> In fact, over the years, I have found it excruciatingly difficult to find
>> valid qemu documentation, as each feature effort tends to leave behind
>> half-updated pages and a bunch of uncoordinated messages about what may or
>> may not have been implemented in unspecified versions.
> I feel your pain and agree.
>
> How can this get improved?
>
> Keeping the command line backward compatible is not an easy task.
>
> There is a quite important effort in progress to improve the documentation.
>
> Users reporting bad/incomplete/outdated documentation would help and motivate 
> developers to fix it. That would reduce the gap between developers 
> implementing features and users.
>
> Do you other have suggestions about what should be improved?

Not related to audio but something as simple as adding a disk is almost 
impossible for a newbie. See this thread for example:

https://lists.nongnu.org/archive/html/qemu-ppc/2020-04/msg00324.html

or this forum post:

https://www.emaculation.com/forum/viewtopic.php?f=34&t=10598

This should be easy to do but even I don't know what's the preferred 
option now and how to use it correctly. Fortunately the -hda and -cdrom 
options still work for some machines, although they produce a warning 
which I tend to ignore as long as it works or go for the long way which is 
impossible to type so I have to save it in a script:

-drive if=none,id=hd,file=harddisk.img,format=raw \
-device ide-hd,drive=hd,bus=ide.0

Probably there should be some sensible way to use QEMU from the command 
line and have some options that work and won't change all the time.

The current situation may be because the CLI and monitor interface that 
are primarily human interfaces are abused by management software as an API 
although probably those should use some real API instead to control QEMU 
and leave the human interface to humans which then can be less arcane and 
have more convenience options. However splitting human and software 
interfaces would probably result in them diverging and human interface 
being neglected and bitrotting so these should be somehow still based on 
some common ground and any change in machine interface should make sure 
human interface is not broken by it.

Regards,
BALATON Zoltan